The present invention relates to a blood reservoir for temporarily storing blood in an extracorporeal blood circulating circuit, and more particularly to a blood reservoir which has a housing including a substantially vertical partition for suppressing resonant vibration of the surface level of blood stored in the blood reservoir upon pulsatory blood feed at the time of discharging the blood.
When a thoracic operation, for example, is to be carried out on a patient, an extracorporeal blood circulating circuit is established using an artificial lung in which the blood is circulated for an exchange of carbon dioxide and oxygen. The blood delivered from the artificial lung is temporarily stored in a blood reservoir for removal of air bubbles from the blood and a steady supply of the blood. Thereafter, the blood is pumped into the patient under the operation at a constant pulse rate.
Blood reservoirs for use in extracorporeal blood circulation include a closed-type blood reservoir in the form of a soft bag for storing blood in an airtight condition and an open-type blood reservoir in the form of a hard housing for storing blood. The open-type blood reservoir is advantageous in that priming and confirmation of the stored amount of blood can easily be performed, and it would be easy to construct the blood reservoir as a unitary component of an artificial lung. An artificial lung with centralized functions, employing an open-type blood reservoir has been proposed by the applicant (see Japanese Laid-Open Patent Publication No. 59-57661).
FIG. 1 of the accompanying drawings schematically illustrates a extracorporeal blood circulating circuit employing an open-type blood reservoir. A blood reservoir 2 stores blood B supplied from an artificial lung (not shown). The blood B is delivered out of the blood reservoir 2 from a blood discharge port 6 defined in the bottom of the reservoir 2 and through a flexible pipe 8. The flexible pipe 8 extends through a pump 10 which includes a rotor 12 that rotates in the direction of the arrows for pulsatively feeding the blood B through the flexible pipe 8 at a certain pulse rate.
The surface level 14 of the blood B stored in the blood reservoir 2 may be subjected to resonant vibration as indicated by the solid and broken lines due to various conditions or parameters such as the pulse rate of the pump 10, i.e., the speed of rotation of the rotor 12, the amount of the blood or the area of the surface level of the blood stored in the blood reservoir 2, and the viscosity of the blood B. When the blood B undergoes such resonant vibration, unwanted vibration tends to be applied to the artificial lung and other components of the extracorporeal blood circulating circuit. The amplitude of the resonant vibration is particularly large if the blood discharge port 6 is positioned asymmetrically with respect to the surface level 14. To avoid this shortcoming, the blood discharge port 6 should preferably be located substantially centrally in the blood reservoir 2. With the blood discharge port 6 thus positioned, however, the configuration and other design factors of the blood reservoir 2 are greatly limited.